Maximum current switch



M. HAUSER MAXIMUM CURRENT SWITCH Flled Oct 28 1955 INSULKI'IDTJ Dec. 27, 1938.

msuumon Patented Dec. 27, 1938 UNITED STATES MAXHHUM CURRENT PATENT OFFICE SWITCH Michael Hauser, Augsburg, Germany 5 Claims.

This invention relates to an arrangement for maximum-current switches, especially those designed as fuse plugs or fuse units.

Such maximum-current switches are already made in a variety of designs, and with thermal release in the event of overload, and with magnetic release in cases of short-circuiting.

It has always hitherto been the practice to employ the magnetic release coils also as blowout coils for the magnetic extinction of arcs, in order, for example, in the event of very serious shorting of direct current, to suppress the formation of arcs rapidly and effectively. Such arrangements, however, have very serious defects, which become manifest in that, for example, the switch chamber must be of corresponding dimensions, in order to enable the arc to spread out sufilciently. This results, in turn, in a considerable disengagement of heat, which extensively burnsaway the contacts, thus again making extremely robust and massive contacts essential. Up to the present, therefore, it has not been possible to construct such apparatus with the minimum dimensions normally required.

It has now transpired that the method heretofore employed for the extinction of arcs, for example in alternating-current apparatus is unsound and that magnetic extinction has a highly injurious effect on the switching devices, such as contacts and luminous-arc chambers. The present invention aims at eliminating the foregoing defects, and at reducing the dimensions of the small switch to a minimum. The existing principle of utilizing-the magnetic release coil for the extinction of arcs is abandoned entirely, and the magnetic release device is so arranged and designed that it cannot have any efiect on the arc. With this and other objects in view according to the invention a magnet system is designed that is thermally quite independent and fully self-contained, and the magnetic flux of which is utilized in such a way that the dimensions of the device can be reduced to an extent hitherto impossible in similar cases. By means of the arrangement of the present invention, in which the lines of magnetic force flow practically free from loss, the number of ampere turns can be reduced to a minimum, and it is possible to manage with a very small arc chamber. Moreover, the arc voltage otherwise occurring during magnetic extinction is obviated by the switch arrangement of the present invention, or is reduced to a fraction of that otherwise occurring.

According to the invention, a highly efiicient combination of the foregoing magnetic release with the thermal release, is obtained by arranging the thermal member, or bimetallic strips, in

eccentric mounted on the release lever, the distance between the same and the bimetallic strips can be controlled in every way. It thus becomes possible to obtain accurate fine adjustment of the release period, and to regulate the distance between the release member and control member within the narrowest limits. In such case, the bimetallic member is preferably designed as free strips arranged on spacing plus, an air space, for the indirect transmission of the heat being interposed between the heating device and the bimetal.

In order more clearly to understand the invention, reference is made to the accompanying drawing, which illustrates diagrammatically and by way of example, one embodiment thereof.

Figure 1 illustrates the switch structure in its closed or operative position.

Figure 2 shows the switch open as a result of either a thermal or magnetic release.

In said drawing, the extended portion of the spring-controlled upright contact pin a, representing the movable member of the switch, is restrained by the locking lever e. The pin a is normally held down on a yielding contact a by a latched bar u, which is unlatched and retracted to permit resetting the mechanism as will hereinafter be described. Said lever carries a cone I, provided with a threaded stem and locked by means of the lock nut h. Seated on a partition '0, which preferably shuts oh the switch chamber, is the bimetallic strip 1', which is mounted on the pins k and is thus brought into a definite position in relation to the heating member I. Between said heating member and the bimetallic strip 1' is interposed-as can be seen-an air space for the purpose of preventing direct transmission of the heat of l to the bimetallic strip.

The thermal release functions in the following manner:--

In the event of an overload, and consequently increased heating, the bimetallic strip i bends towards the left, until it touches the cone f on the lever e and thereby releases the lever hook w from the upper end c of the contact pin a. The release period is determined by the heat generated, and particularly by the distance between the release mem'berin this case the lever e and cone f--and the control member 2.

It is evident that the distance between i and f can be increased or diminished in a simple manner, by turning the cone 1 to the right or left in the lever e, by means of its threaded stem 9, and

securing it in the correct position by means of the 5 Disposed on the opposite side of the switch pin 60 a is the magnet frame, which is formed by the limbs m, n and completely shut off from the switch chamber. The magnet winding is mounted on the limb n. The magnet unit acts upon a magnetic armature o, rockably mounted, about the point cu, in a lever r rotatably mounted on a fixed support a: after the manner of a balance beam. In the event of a short circuit, for example, the opposite end of the lever r strikes against the cone 1 on the locking lever e, which releases the axially spring-controlled contact pin a. The armature 0 is situated on a freely swinging threaded pin. suspended on the point ya and rests against a non-magnetic carrier plate under the pressure of a non-magnetizable spring. The armature o is adjusted on the pin by screwing it up and down, and it is secured by means of the lock nut p. Manual release of the arrangement is effected from outside, by applying pressure to a knob s, also on the lever r.

The circuit passes from the central contact a to the contact pin a, thence to the heating memher I and the magnet coil 11, and to the shell 1..

The bar u, which may be part of a push button, is normally held latched in the position shown by a latch 11 pivoted on the support a: and holds the contact pin a against the yielding contact a, by means of the lever 0, thus holding the circuit closed. If an overload causes the bimetallic member 1 or the magnet coil 11 to trip the lever e the shoulder w on the lever e releases the contact pin a so that its spring b breaks the contact between a and a.

To reset the switch the bar it is retracted to allow the lever e to drop by gravity into latching engagement with the end c of the contact pin a whereupon the bar u is manually returned to the position shown in Figure l to reestablish contact between pin a and contact a.

The operation of opening the switch may result from the thermal or magnetic releases or from a manual operation of the button s, in each case resulting in movement of the lever e to release the shoulder 11; from the top of the extension 0. As the extension 0 moves upward under the influence of the spring b it contacts the latch 11 and pushes it aside against a spring z, thus releasing the bar u, which moves into the position of Figure 2 where the lever e swings into the position shown with the shoulder w in operative contact with the extension 0 so that pushing the bar a to the position of Figure 1 will return the switch contacts a and a into contact at the same time the latch y reengages its notch in the bar u to retain the switch in its closed position.

I claim:

1. A plug type switch comprising a casing, a first switch contact member, a second and elongated switch contact member normally springurged to circuit-opening position, a manually depressible and spring-opposed member extending through a wall of said casing and in aligned longitudinal relation to said elongated switch contact member, a first latch pivoted on said depressible member and movable therewith to effect movement of said second switch contact member to circuit closing position, a second latch member arranged to engage said depressible member and retain it in depressed position, and current-responsive means in said casing operative to move said first latch to effect release of said second switch member and for release 01' said second latch through switch-opening movement of said second switch member.

2. A switch comprising a casing, a first switch contact member, a second and elongated switch contact member normally spring-urged to circuit opening position, a manually operated and spring-opposed member movable in longitudinally aligned relation to said second switch member, a first latch pivoted on said manually operable member and movable therewith to engage and effect movement of said second switch member to closing position, a second latch member arranged to engage said manually operable member to retain said member in switch closing position, current-responsive means movable to trip said first latch and effect release of said second switch member and to effect tripping of said second latch member through movement of said second switch member.

3. A switch comprising a first switch contact member, a second switch contact member normally spring-urged to switch opening position, manually operable and spring-opposed means including a first clutch movable to engage said second switch member to effect movement of said second switch member to switch closing position, a second clutch arranged to engage said manually operable means to retain said means in switch closing position, current-responsive means movable to trip said first clutch and effect release of said second switch member, said second switch member being arranged movable when released to effect tripping of said second clutch to effect release of said manually operable means.

4. A switch comprising a first switch contact member, a second switch contact member normally spring-urged to switch opening position, a first manually operable and spring-opposed means including a first clutch movable to engage said second switch member to effect movement of said second switch member to switch closing position, a second clutch arranged to engage said first manually operable means to retain said means in switch closing position, currentresponsive means movable to trip said first clutch and efifect release of said second switch member, a second manually operable means movable to trip said first clutch and effect release of said second switch member, said second switch member being arranged movable when released to effect tripping of said second clutch to effect release of said first manually operable means.

5. A switch comprising a first switch contact member, a second switch contact member normally spring-urged to switch opening position, manually operable and spring-opposed means including a first clutch member movable to engage said second switch member to effect movement of said second switch member to switch closing position, a second clutch member arranged to engage said manually operable means to retain said means in switch closing position, a currentheated element and a bimetallic member responsive to heat from. said current-heated element and movable to effect movement of said first clutch to release said second switch member for movement to switch open position, said second switch member being arranged movable when released to trip said second clutch member.

MICHAEL HAUSER. 

